This invention relates to methods of anchoring leads to ceramic bodies.
Ceramic materials have found extensive use, for example, in the manufacture of electron discharge display devices. For this and other applications, it is desirable to secure or anchor a plurality of leads within openings of a fired ceramic body (i.e., provide lead retension therein). The leads, for example, may comprise: wires, ribbons, pins, filaments or posts. It is also desirable in such applications to provide a mechanical anchoring or these various "leads" which is strong and capable of withstanding large temperature differentials. One such application is the anchoring of filamentary mounting posts in apertures of a ceramic substrate used within envelopes of filamentary display devices such as depicted in U.S. Pat. No. 3,564,325 issued to R. A. Bonnette and N. L. Lindburg on Feb. 16, 1971.
A simple inexpensive anchoring method is desirable for such applications permitting the use of materials having substantially different coefficients of thermal expansion. Prior art methods have, for example, limited material selection and/or have required the costly and time consuming application of metallization pastes or coatings of ceramic-metal powders on inner wall surfaces of openings provided in the ceramic body. Examples of such methods are for example, described in U.S. Pat. No. 3,241,995 issued to H. Pulfrich et al on Mar. 22, 1966; U.S. Pat. No. 3,010,188 issued to A. Bol et al on Nov. 28, 1961; and U.S. Pat. No. 3,180,020 issued to W. W. Allen et al, on Apr. 27, 1965. The prior art techniques, and others, are, for example, explained in greater detail in W. H. Kohl, Material and Techniques for Electron Tubes N. Y., Reinhold, 1960.
Yet another approach is, for example, described in U.S. Pat. No. 3,024,300 issued to I. E. Martin on Mar. 6, 1962, wherein the application of a compressional axial force at a sealing interface between a ceramic and metallic cylindrical body causes a deformable coating on one member to flow to form a sealing gasket at the interface. This and other compressional type sealing methods are generally impractical for anchoring a plurality of leads to a single substrate. The compressional forces required may, for example, deform or break small leads. Also, the sealing of individual leads would be time consuming and result in costly assembly.